China seems poised to launch three astronauts into space, in the middle of June, onboard Shenzhou 9, the country's fourth, and most ambitious manned spaceflight.

Shenzhou 9 is scheduled to rendezvous and complete a manual docking with the orbiting Tiangong 1 module, and will stay in orbit for 13 days, more than doubling China's current endurance record.

The Long March 2F rocket was delivered to the Jiuquan Satellite Launch Centre on 9th May, and it is now being checked and assembled for flight. The Shenzhou 9 spacecraft itself had arrived at Jiuquan a month earlier.

Although Chinese media, and officials, are still referring to a planned launch between 'June and August', with all hardware now at Jiuquan, it seems that the Chinese are working towards a launch in the earlier part of that timeframe. Previous Shenzhou flights, whether manned or unmanned, have launched only 35-40 days after the arrival of the rocket at Jiuquan

In addition, the respected UK based space and satellite tracking service, www.zarya.info , has undertaken ongoing analysis of the orbital track of Tiangong 1 since it was launched last year.

Zarya is now able to anticipate an eight day launch window, for Shenzhou 9, which would accommodate a two day orbital chase to rendezvous and dock with Tiangong 1, and then return to earth after 13 days, in the established recovery zone. This launch window opens in 17th June, which is 39 days after the Long March was delivered to the launch centre.

Chinese officials have previously said that Shenzhou 9's flight will include a 10 day stay at Tiangong 1.

The Tiangong-1, which was launched on Sept. 29, 2011, was instrumental in China's first space docking mission, in which the unmanned Shenzhou-8 spacecraft docked with the Tiangong-1 in early November 2011. If all goes well with Shenzhou 9, another crew will visit the Tiangong 1 outpost in 2013 onboard Shenzhou 10.